1. Field of the Invention
This invention relates to a medical instrument. More particularly this invention relates to a medical instrument formed of a laminate of flexible vinyl chloride resin. This medical instrument has the inner wall thereof embossed to preclude the problem of blocking otherwise occurring between the opposed portions of the inner wall.
2. Description of the Prior Art
The flexible vinyl chloride resin enjoys outstanding processibility, absolute physiological safety, high transparency, and inexpensiveness and, owing to these features, finds extensive utility in various medical instruments such as blood bags, transfusion bags, dialytic solution bags, and connection tubes.
In the medical instrument made of flexible vinyl chloride resin, however, owing to the migration of the plasticizer persisting in the flexible vinyl chloride resin, for example, the opposed portions of the inner walls of such instruments adhere to each other and induce the phenomenon of blocking. Consequently, these instruments have the possibility that their entrances will not readily open and their interiors will not readily admit medical preparations, blood, etc. Further in the case of tubular medical instrument, there is the possibility that their inner walls induce blocking of passage where they are bent.
As means of preventing the flexible vinyl chloride resin film from inducing the blocking, there is adopted, during the processing of the flexible vinyl chloride resin film, for example, a method whereby an embossing surface is formed on the backup roll incorporated in the sheet winding machine so as to impart protuberances on one surface of the sheet. This method has the disadvantage that the operation of this method necessitates use of an expensive embossing roll, the embossing surface of the roll is flattened by protracted use and, therefore, cannot continue to provide uniform embossing for a long time, and the method itself is not applicable to the inner surface of sheet in the inflation molding. There has also been proposed a method wherein a land portion near a die lip is cooled to differentiate the flow of resin on the outer surface and the inner surface of a film, induce convolution in the flow of resin and, as the result, corrugate the inner surface of the film and effect embossing of the surface (Japanese Patent Laid-Open No. SHO 50(1975)-55,679). Adoption of this method, however, adds to the number of restrictions imposed on the molding operation and degrades the capacity for mass-production. Moreover, the condition of embossing by this method is difficult to control and the embossing actually obtained lacks uniformity. A method which precludes the blocking by spraying of talc on the film surface and a method which avoids the blocking by having the flexible vinyl chloride resin incorporate therein in advance a lubricant such as stearic acid or palmitic acid thereby allowing the lubricant to imigrate to the surface of the film and impart activity thereto. The method which resorts to spray of talc entails deposition of talc as foreign matter on the film surface and, therefore, contamination of the fluid by the foreign matter, a fact which is detrimental to most purposes, let along medical treatment. The method which relies on the incorporation of a lubricant has the disadvantage that the lubricant will cause the phenomenon of blooming and the surface of flexible vinyl chloride resin film will be defiled with elapse of time.
As described above, none of the methods heretofore developed for the prevention of the flexible vinyl chloride resin film from the blocking proves fully effective as expected. Thus, the medical instruments made of flexible vinyl chloride resin are still used, with the problem of blocking pending solution.
An object of this invention, therefore, is to provide a novel medical instrument.
Another object of this invention is to provide a medical instrument, protected against the blocking due to adhesion between the opposed portions of the inner wall thereof.
Yet another object of this invention is to provide a medical instrument which is useful as a transfusion bag, a blood bag, a dialytic solution bag, and particularly a bag for CAPD medicine.
Still another object of this invention is to provide a medical instrument which will not induce the blocking even after sterilization by autoclaving.
A further object of this invention is to provide a medical instrument adapted so that the transparency of the apparatus will be increased by the presence of the fluid in the interior of the apparatus to a point where the fluid held therein can be visually observed from outside.